Bead-type shaped articles produced by using biopolymers (for example, proteins, polysaccharides and the like) have been utilized as bead foods and as supports for immobilizing physiologically active substances.
As a bead-type food, for example, Japanese Patent Laid-Open No. 79755/1976 proposes a process for producing a fish roe-like food which comprises gelatinizing cold-gelling and edible aqueous sol droplets (for example, gelatin) by cooling, further coating the gelatinized particles thus formed with a film-forming sol and contacting the same with a gelling agent to thereby form a gelatinized film layer. Further, Japanese Patent Publication No. 11101/1970 proposes to provide gelatinized alginate particles by treating an alginate with a divalent metal ion which can be incorporated into the body of a living organism.
As a bead-type shaped article produced with the use of collagen, Japanese Patent Publication No. 1169/1989 describes a process for producing collagen beads which are usable as a support for immobilizing a physiologically active substance. This process comprises forming collagen spheres in an organic solvent which is hardly miscible or immiscible with water and then hardening the spheres.
However there has been developed no bead-type shaped collagen article which is applicable to foods.
In the conventional methods for producing collagen beads as described above, an aqueous liquid of a high concentration of a collagen material is employed and a hardly miscible or immiscible organic solvent is used during the production process. In general, many hardly miscible or immiscible organic solvents are harmful to human beings. Therefore, the production of beads with the use of such organic solvents suffers from problems of the contamination and remaining of the organic solvents in the beads. In the conventional methods, furthermore, aldehydes and metal salts such as chromium salts are used in order to harden or crosslink collagen. Therefore, the beads thus obtained are hardly applicable to foods.